This invention relates to new metallocene compounds useful as a catalyst component for olefin polymerization. More particularly, the invention relates to metallocene compounds having an indenyl ligand substituted by a heteroaromatic group and catalysts for olefin polymerization containing said metallocene compounds.
As a catalyst component which can be used in the polymerization of olefins, conventional Ziegler-Natta catalysts have been partly replaced by the metallocene compounds wherein a multidentate compound containing a xcfx80-electron donor such as unsubstituted or substituted cycloalkadienyl groups is coordinated to a transition metal atom, said cycloalkadienyl groups including, e.g., unsubstituted or substituted cyclopentadienyl, indenyl, tetrahydroindenyl and fluorenyl groups.
In recent years, various metallocene compounds having an improved olefin polymerization activity per mole of a transition metal atom have been proposed. It is known that polymers of xcex1-olefin having high stereoregularity, in particular, propylene polymers having high stereoregularity can be preferably prepared by using a metallocene compound having a C2 symmetry as a catalyst component, wherein a multidentate compound having two substituted cycloalkadienyl groups bonded with a divalent linking group is coordinated to a transition metal atom (J. Am. Chem. Soc. 1998, 120, 11316-11322).
Further, the development of metallocene compounds with a high olefin polymerization activity has been continued. Various metallocene compounds have been proposed wherein a heteroatom is introduced into the substituent or the cycloalkadiene ring in the substituted cycloalkadienyl group. For instance, Japanese Patent Kokai 7-258282 discloses metallocene compounds wherein two indenyl ligands are linked to each other through a linking group and a saturated group containing a heteroatom such as nitrogen, phosphorus, arsenic, antimony or bismuth is directly linked to a carbon group at the 2-position of the indenyl groups through the heteroatom, and specifically, dimethylsilanediylbis(2-pyrrolidino-1-indenyl)zirconium dichloride.
Japanese Patent Kokai 8-183814 discloses metallocene compounds wherein two indenyl ligands are linked to each other through a linking group and the indenyl ligand is substituted by a 1-pyrrolyl group, a 1-indolyl group or the like at the 4-position, and specifically, dimethylsilylenebis(4-(1-indolyl)-2-methylindene)zirconium dichloride.
J. Am. Chem. Soc. 1998, 120, 10786-10787 discloses metallocene compounds wherein a heteroatom-containing cycloalkadiene having a thiophene ring or a pyrrol ring condensed to a cyclopentadiene ring is linked through a divalent linking group and coordinated to a transition metal atom.
Japanese Patent Publication 9-510745 discloses bis(2-phenylindenyl)zirconium dichloride as a non-bridged indenyl complex capable of producing a stereo block polypropylene which is a elastomeric polyolefin.
Elastomeric polyolefins having a rubber elasticity have attracted the attention of those skilled in the art recently. A new catalyst for efficiently producing elastomeric polyolefins has been desired, but the conventional catalysts as mentioned above do not meet the demands.
An object of the present invention is to provide a catalyst for efficiently producing elastomeric polyolefins having a high heat resistance.
The present inventors have made earnest studies to accomplish the above object and found that elastomeric polyolefins can be produced efficiently by using as a catalyst component metallocene compounds having two indenyl ligands wherein the indenyl ligand is substituted by a heteroaromatic group preferably at a specific position, and also that elastomeric polyolefins with a high heat resistance can be produced efficiently by using as a catalyst component metallocene compounds wherein the indenyl ligand is substituted by a furyl group at the 2-position.
The present invention relates to a metallocene compound having an indenyl ligand represented by the following formula (1) 
wherein M represents a transition metal atom in Group 3 including lanthanoid and actinoid series, or Group 4 or 5 of the periodic table;
each Ra independently represents a monocyclic or polycyclic heteroaromatic group containing a heteroatom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom;
each R1 independently represents a halogen atom, a hydrocarbon group of 1-20 carbons, a halogenated hydrocarbon group of 1-20 carbons, a silyl group substituted by said hydrocarbon group or said halogenated hydrocarbon group, an amino group substituted by said hydrocarbon group, or a monocyclic or polycyclic amino group, and adjacent R1""s may be joined together to form a ring of 6-8 carbons;
p and q are each independently an integer of 1-7;
n and l are each independently 0 or an integer of 1-6; and
X each independently represents a halogen atom, a hydrocarbon group of 1-20 carbons, a halogenated hydrocarbon group of 1-20 carbons, or a silyl group substituted by said hydrocarbon group or said halogenated hydrocarbon group; and a catalyst for olefin polymerization comprising said metallocene compound.
In the formula (1) which represents the metallocene compounds of the present invention, M represents a transition metal atom in Group 3 including lanthanoid and actinoid series, or Group 4 or 5 of the periodic table, and preferably, titanium, zirconium or hafnium.
Each Ra independently represents a monocyclic or polycyclic heteroaromatic group containing a heteroatom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom, which links to the 5- or 6-membered ring of the indenyl ligand. For example, the monocyclic or polycyclic heteroaromatic groups containing an oxygen atom can include furyl and benzofuryl, and furyl groups can include 2-furyl and 3-furyl.
The monocyclic or polycyclic heteroaromatic groups containing a sulfur atom can include thienyl and benzothienyl, and thienyl groups can include 2-thienyl and 3-thienyl.
The monocyclic or polycyclic heteroaromatic groups containing a nitrogen atom can include pyrrolyl, pyridyl, indolyl and quinolyl. Pyrrolyl groups can include 1-pyrrolyl, 2-pyrrolyl and 3-pyrrolyl; pyridyl groups can include 2-pyridyl, 3-pyridyl and 4-pyridyl; indolyl groups can include 1-indolyl and 3-indolyl; and quinolyl groups can include 1-quinolyl and 3-quinolyl.
The heteroaromatic group Ra may be substituted by a substituent such as an alkyl group, an aryl group, an aralkyl group, an alkoxy group, a substituted silyl group and a halogen atom. The adjacent substituents may be joined together to form a condensed ring. Typical examples of the substituents can include methyl, ethyl, tert-butyl, phenyl, vinyl, methoxy, trimethylsilyl, vinyldimethylsilyl, phenyldimethylsilyl, methoxydimethylsilyl and fluoro. A typical example of the condensed ring is a benzene ring.
Preferable heteroaromatic groups are 2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 2-pyrrolyl, 3-pyrrolyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, benzofuryl, benzothienyl, 3-indolyl, 1-quinolyl and 3-quinolyl. More preferable is furyl and particularly preferable is 2-furyl.
Unsubstituted or substituted 2-furyl groups can include 2-furyl, 2-(5-methyl)furyl, 2-(5-t-butyl)furyl, 2-(5-trimethylsilyl)furyl, 2-(5-phenyl)furyl, 2-(5-vinyldimethylsilyl)furyl, 2-(4,5-benzofuryl), 2-(4,5-dimethyl)furyl and 2-(5-fluoro)furyl. For the production of elastomeric polyolefins with a high heat resistance, it is preferable that at least one of these heteroaromatic groups is linked to the 5-membered ring of the indenyl ligand. More preferably, the heteroaromatic group is linked at the 2-position of the indenyl ligand.
Preferable metallocene compounds of the present invention are the compounds of the formula (1) wherein two heteroaromatic group Ra""s are furyl and each furyl group is bonded at the 2-position of two indenyl ligands.
More preferable metallocene compounds of the present invention are the compounds of the formula (1) wherein two heteroaromatic group Ra""s are furyl and each furyl group has the substituent and is further bonded at the 2-position of two indenyl ligands. Preferable metallocene compounds for the production of highly stereoregular olefin polymers are those wherein the substituent is bonded at the 5-position of the furyl group. Most preferable metallocene compounds are those wherein each furyl group bonded at the 2-position of two indenyl ligands has a substituent at the 5-position. Typical Examples of the substituents can include an alkyl group, an aryl group, an aralkyl group, an alkoxy group, a substituted silyl group and a halogen atom, and more specifically, methyl, ethyl, tert-butyl, phenyl, vinyl, methoxy, trimethylsilyl, vinyldimethylsilyl, phenyldimethylsilyl, methoxydimethylsilyl and fluoro. Further, the adjacent substituents may be joined together to form a condensed ring, a typical example of which is a benzo ring.
Most preferable furyl groups wherein the substituent is bonded at the 5-position can include 2-(5-methyl)furyl, 2-(5-t-butyl)furyl, 2-(5-phenyl)furyl, 2-(5-trimethylsilyl)furyl, 2-(5-vinyldimethylsilyl)furyl, 2-(4,5-benzofuryl), 2-(4,5-dimethyl)furyl and 2-(5-fluoro)furyl.
Each R1 independently represents a halogen atom, a hydrocarbon group of 1-20 carbons, a halogenated hydrocarbon group of 1-20 carbons, a silyl group substituted by said hydrocarbon group or said halogenated hydrocarbon group, an amino group substituted by said hydrocarbon group, or a monocyclic or polycyclic amino group.
The halogen atoms can include, e.g., fluorine, chlorine, bromine and iodine.
The hydrocarbon groups of 1-20 carbons can include an alkyl group of 1-20 carbons, an aryl group of 6-20 carbons, an aralkyl group of 7-20 carbons, an alkoxy group of 1-20 carbons, an aryloxy group of 6-20 carbons and an aralkyloxy group of 7-20 carbons.
The alkyl groups of 1-20 carbons can include straight- or branched-chain alkyl groups, for example, methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, tert-butyl, sec-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl and octadecyl, and cyclic alkyl groups which may be substituted by said chain alkyl groups, for example, cyclopropyl, cycloheptyl and cyclohexyl.
The aryl groups of 6-20 carbons can include, for example, phenyl, naphthyl and anthryl; and those groups which are further substituted by said alkyl group, for example, tolyl, xylyl and trimethylphenyl.
The aralkyl groups of 7-20 carbons can include, for example, benzyl, naphthylmethyl and anthrylmethyl; and those groups which are further substituted by said alkyl group, for example, (methylphenyl)methyl, (dimethylphenyl)methyl, (trimethylphenyl)methyl, (ethylphenyl)methyl, (propylphenyl)methyl and (butylphenyl)methyl.
The alkoxy groups of 1-20 carbons can include chain and cyclic alkoxy groups having said alkyl group, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, hexyloxy and cyclohexyloxy.
The aryloxy groups of 6-20 carbons can include substituted or unsubstituted aryloxy groups having said aryl group, for example, phenoxy, naphthyloxy and anthryloxy.
The aralkyloxy groups of 7-20 carbons can include, for example, aralkyloxy groups having said aralkyl groups such as benzyloxy.
The halogenated hydrocarbon groups of 1-20 carbons can include halogenated alkyl groups, halogenated aryl groups, halogenated aralkyl groups, halogenated alkoxy groups, halogenated aryloxy groups and halogenated aralkyloxy groups, for example, monochloromethyl, dichloromethyl, trichloromethyl, perfluoroethyl, monochlorophenyl, difluorophenyl and monochlorobenzyl.
The silyl groups substituted by said hydrocabon groups can include those which are tri-substituted by said hydrocarbon group, e.g., trimethylsilyl, triethylsilyl, triphenylsilyl, tribenzylsilyl, triethoxysilyl and dimethylphenoxysilyl. The silyl groups substituted by said halogenated hydrocarbon groups can include (trifluoromethyl)dimethylsilyl, (fluorophenyl)dimethylsilyl, and (chloromethyl)dimethylsilyl.
The amino groups substituted by said hydrocarbon groups can include those which are di-substituted by said hydrocarbon groups, for example, dimethylamino, diethylamino and methylethylamino. The monocyclic amino groups may be saturated or unsaturated, which can include, e.g., 1-pyrrolidyl and 1-pyrrolyl. The polycyclic amino groups may be saturated or unsaturated, which can include, e.g., 1-indolyl.
In the metallocene compounds of the present invention, it is preferable that the substituent R1 on the indenyl group is aryl or benzo, because olefin polymers of higher molecular weight can be produced. It is especially preferable that aryl or benzo is introduced at the 4-position of the indenyl group. Examples of such substituents can include 4-phenyl, 4-naphthyl and 4,5-benzo.
p and q represent the number of Ra and each is independently an integer of 1-7, preferably 1-3.
n and l represent the number of R1 and each is independently 0 or an integer of any one of 1-6, preferably 0 or an integer of any one of 1-4.
X each independently represents a halogen atom, a hydrocarbon group of 1-20 carbons, a halogenated hydrocarbon group of 1-20 carbons, or a silyl group substituted by said hydrocarbon group or said halogenated hydrocarbon group. Each X has the same definition as defined above for R1, but X and R1 are independent from each other. X is preferably a halogen atom, and more preferably chlorine.
Non-limitative examples of the metallocene compounds according to the present invention can include bis(2-(2-furyl)indenyl)zirconium dichloride, bis(2-(2-furyl)indenyl)zirconium dibromide, bis(2-(2-furyl)indenyl)zirconium methylchloride, bis(2-(2-furyl)indenyl)zirconium diemthyl, bis(2-(2-furyl)indenyl)zirconium diphenyl, bis(2-(2-thienyl)indenyl)zirconium dichloride, bis(2-(N-pyrrolyl))indenyl)zirconium dichloride, bis(2-(2-pyridyl)indenyl)zirconium dichloride, bis(2-(2-benzofuryl)indenyl)zirconium dichloride, bis(2-(2-indolyl)indenyl)zirconium dichloride, bis(2-(2-quinolyl)indenyl)zirconium dichloride, bis(2-(2-furyl)-1-methylindenyl)zirconium dichloride, bis(2-(2-furyl)-4-methylindenyl)zirconium dichloride, bis(2-(2-furyl)-4-phenylindenyl)zirconium dichloride, bis(2-(2-furyl)-4-naphthylindenyl)zirconium dichloride, bis(2-(2-furyl)-4,5-benzoindenyl)zirconium dichloride, bis(2-(2-furyl)cyclopentaphenanthryl)zirconium dichloride, bis(2-(2-furyl)4-phenyl-7-methyl-indenyl)zirconium dichloride, bis(2-(2-(5-trimethylsilyl)furyl)indenyl)zirconium dichloride, bis(2-(2-(5-vinyldimethylsilyl)furyl)indenyl)zirconium dichloride, bis(2-(2-(5-phenyl)furyl)indenyl)zirconium dichloride, bis(2-(2-(5-methyl)furyl)indenyl)zirconium dichloride, bis(2-(2-(4,5-dimethyl)furyl)indenyl)zirconium dichloride, bis(2-(2-(5-trimethylsilyl)furyl)-4-phenylindenyl)zirconium dichloride, bis(2-(2-(5-trimethylsilyl)furyl)-4,5-benzoindenyl)zirconium dichloride, bis(4-(2-furyl)-2-phenylindenyl)zirconium dichloride, bis(4-(1-pyrrolyl)-2-phenylindenyl)zirconium dichloride, bis(4-(1-indolyl)-2-phenylindenyl)zirconium dichloride, bis(2-(2-furyl)indenyl)hafnium dichloride, bis(2-(2-furyl)indenyl)hafnium dibromide, bis(2-(2-furyl)indenyl)hafnium methylchloride, bis(2-(2-furyl)indenyl)hafnium dimethyl, bis(2-(2-furyl)indenyl)hafnium diphenyl, bis(2-(2-thienyl)indenyl)hafnium dichloride, bis(2-(2-pyrrolyl)indenyl)hafnium dichloride, bis(2-(2-pyridyl)indenyl)hafnium dichloride, bis(2-(2-benzofuryl)indenyl)hafnium dichloride, bis(2-(2-indolyl)indenyl)hafnium dichloride, bis(2-(2-quinolyl)indenyl)hafnium dichloride, bis(2-(2-furyl)-1-methylindenyl)hafnium dichloride, bis(2-(2-furyl)-4-methylindenyl)hafnium dichloride, bis(2-(2-furyl)-4-phenylindenyl)hafnium dichloride, bis(2-(2-furyl)-4-naphthylindenyl)hafnium dichloride, bis(2-(2-furyl)-4,5-benzoindenyl)hafnium dichloride, bis(2-(2-furyl)cyclopentaphenanthryl)hafnium dichloride, bis(2-(2-furyl)indenyl)titanium dichloride, bis(2-(2-furyl)indenyl)titanium dibromide, bis(2-(2-furyl)indenyl)titanium methylchloride, bis(2-(2-furyl)indenyl)titanium dimethyl, bis(2-(2-furyl)indenyl)titanium diphenyl, bis(2-(2-thienyl)indenyl)titanium dichloride, bis(2-(2-pyrrolyl)indenyl)titanium dichloride, bis(2-(2-pyridyl)indenyl)titanium dichloride, bis(2-(2-benzofuryl)indenyl)titanium dichloride, bis(2-(2-indolyl)indenyl)titanium dichloride, bis(2-(2-quinolyl)indenyl)titanium dichloride, bis(2-(2-furyl)-1-methylindenyl)titanium dichloride, bis(2-(2-furyl)-4-methylindenyl)titanium dichloride, bis(2-(2-furyl)-4-phenylindenyl )titanium dichloride, bis(2-(2-furyl)-4-naphthylindenyl)titanium dichloride, bis(2-(2-furyl)-4,5-benzoindenyl)titanium dichloride, bis(2-(2-furyl)cyclopentaphenanthryl)titanium dichloride, bis(2-(2-(5-fluoro)furyl)indenyl)zirconium dichloride, bis(2-(2-(5-fluoro)furyl)-4,5-benzoindenyl)zirconium dichloride, bis(2-(2-(5-fluoro)furyl)-4-phenylindenyl)zirconium dichloride, bis(2-(2-(5-fluoro)furyl)cyclopentaphenanthryl)zirconium dichloride, bis(2-(2-(5-methyl)furyl)cyclopentaphenanthryl)zirconium dichloride, bis(2-(2-(5-trimethylsilyl)furyl)cyclopentaphenanthryl)zirconium dichloride, bis(2-(2-(5-phenyl)furyl)cyclopentaphenanthryl)zirconium dichloride, bis(2-(2-(5-fluoro)furyl)cyclopentaphenanthryl)zirconium dichloride, bis(2-(2-benzofuryl)cyclopentaphenanthryl)zirconium dichloride, (2-(2-(5-methyl)furyl)cyclopentaphenanthryl)(2-(2-(5-methyl)furyl)indenyl)zirconium dichloride, bis(2-(2-(5-methyl)furyl)-5,6-bis(trimethylsilyl)indenyl)zirconium dichloride and bis(2-(2-(5-methyl)furyl)-5,6-bis(trimethylsilyl)indenyl)hafnium dichloride.
As a method for the synthesis of a ligand, known methods can be employed. For example, xe2x80x9cTetrahedron Letters, 35, 4, 633-636, (1994)xe2x80x9d discloses 2-furyl indene and 2-thienyl indene. As a method for the synthesis of an indene substituted by a heteroaromatic group, there is a method wherein a halogenated indene and a boronic acid derivative of an heteroaromatic compound are subjected to cross coupling in the presence of a catalyst. For instance, 2-(2-furyl)indene can be synthesized by subjecting 2-bromo indene and 2-furyl boronic acid to cross coupling with a Pd metal in the presence of a base.
A representative synthesis route of the metallocene compound of formula (1) according to the present invention is illustrated below, but not limited thereto.
xe2x80x83RaR1xe2x80x94C9H6+nxe2x80x94BuLixe2x86x92Li(RaR1xe2x80x94C9H5)+C4H10xe2x80x83xe2x80x83[1]
2 Li(RaR1xe2x80x94C9H5)+MX4xe2x86x92(RaR1xe2x80x94C9H5)2MX2+2 LiXxe2x80x83xe2x80x83[2]
More specifically, the metallocene compound of formula (1) is prepared by a process comprising step [1] of anionizing an indene substituted by a heteroaromatic group with a metal salt type base and step [2] of reacting the anionized, substituted indene, for instance, with a metal halide.
Examples of metal salt type bases used in the anionization of the heteroaromatic group-substituted indene in step [1] can include methyllithium, n-butyllithium, t-butyllithium, phenyllithium, lithium hydride, sodium hydride, potassium hydride, calcium hydride, lithium diisopropylamide, t-butyloxypotassium, methylmagnesium iodide, ethylmagnesium iodide, phenylmagnesium bromide, and t-butylmagnesium bromide.
The anionization reaction of the heteroaromatic group-substituted indene can be carried out with said metal salt type base in the presence of an amine compound which includes primary amines, e.g., methylamine, ethylamine, n-propyl-amine, isopropylamine, n-butylamine, tert-butylamine, aniline and ethylenediamine; secondary amines, e.g., dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, di-tert-butylamine, pyrrolidine, hexamethyldisilazane and diphenylamine; and tertiary amines, e.g., trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tri-tert-butylamine, triphenylamine, N,N-dimethylaniline, N,N,Nxe2x80x2,Nxe2x80x2-tetramethylethylenediamine, N-methylpyrrolidine and 4-dimethylaminopyridine.
The anionization reaction of the substituted indene is usually carried out in an organic solvent at a reaction temperature between not lower than xe2x88x92100xc2x0 C. and not higher than a boiling point of the solvent used, preferably in the range of xe2x88x9270xc2x0 C. to 100xc2x0 C.
The organic solvents used in the reaction can be used without any limitation, unless they are reactive to the starting compounds or reaction products or decompose them. Preferably, ethers, halogenated hydrocarbons or aromatic compounds can be used. For ethers, preferable are relatively low-molecular ethers such as diethylether, diisopropylether, tetrahydrofuran and dimethoxyethane. Dichloromethane is preferable for halogenated hydrocarbons. For aromatic compounds, preferable are toluene, anisol and xylene. Further, a mixed solvent of these two or more compounds can be used.
Examples of metal halides reacted with the anionized, substituted indene in step [2] can include metal tetrahalides or metal tri- or di-halides wherein up to two halogen atoms are substituted by said hydrocarbon group, said halogenated hydrocarbon group or said silyl group, for example, titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrafluoride, titanium trichloride, titanium tribromide, titanium triiodide, titanium trifluoride, zirconium tetrachloride, zirconium tetrabromide, zirconium tetraiodide, zirconium tetrafluoride, hafnium tetrachloride, hafnium tetrabromide, hafnium tetraiodide and hafnium tetrafluoride. Preferable are metal tetrahalides.
The metallocene compound is isolated and purified from the reaction solution after the reaction in step [2] by a conventional method. The purification can be performed by distilling the solvent off, or by extraction with a suitable solvent, adsorption, filtration, recrystallization or the like, as the occasion demands. Usually, a desired product can be crystallized out by utilizing the difference between the desired product and impurities in solubility in a solvent, and further purified by recrystallization or the like to prepare the metallocene compound of the present invention.
The present metallocene compound of the formula (1) used together with aluminoxane, an ionic compound or a mixture of an ionic compound and an organoaluminum compound, as a catalyst for olefin polymerization, exhibits an excellent polymerization activity.
Aluminoxanes are organoaluminum compounds represented by the following formula (2) or (3) or the mixture thereof. 
In the formulae (2) and (3), each R2 and R3 independently represent a hydrogen atom or a hydrocarbon group of 1-20 carbons, m represents an integer of 4-30 and r represents an integer of 6-32.
Examples of the hydrocarbon group of 1-20 carbons can include an alkyl group such as methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl, etc.; an alkenyl group such as allyl, 2-methylallyl, propenyl, isopropenyl, 2-methyl-1-propenyl, butenyl, etc.; a cycloalkyl group such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.; and an aryl group, etc. Preferable is a hydrocarbon group of 1-6 carbons, and more preferable is that of 1-4 carbons.
In the formula (2), m is an integer of 4 to 30, preferably 6 to 30, and more preferably 8 to 30.
In the formula (3), r is an integer of 6 to 32, preferably 8 to 32, and more preferably 10 to 32.
In case where at least two R2""s are identical in the formula (2) and at least two R3""s are identical in the formula (3), each R2 and R3 are independently and preferably a hydrocarbon group such as methyl, ethyl, propyl, isobutyl, phenyl and benzyl, and most preferably methyl.
In case where at least one R2 is not identical in the formula (2) and at least one R3 is not identical in the formula (3), each R2 and R3 are independently and preferably a combination containing methyl and hydrogen or a combination containing methyl and isobutyl, and more preferably a combination consisting of methyl and hydrogen or a combination consisting of methyl and isobutyl. In case where R2 and R3 are composed of a combination consisting of methyl and hydrogen, the proportion of the number of hydrogen to the sum total of methyl and hydrogen is preferably in the range of 0.01-60%. In case where R2 and R3 are composed of a combination consisting of methyl and isobutyl, the proportion of the number of isobutyl to the sum total of methyl and isobutyl is preferably in the range of 0.01-60%.
The above-mentioned aluminoxanes can be prepared by various known methods, examples of which are recited below.
[1] A method of reacting a trialkyl aluminum directly with water in an organic solvent such as toluene and ether;
[2] A method of reacting a trialkyl aluminum with salts containing crystal water, e.g., copper sulfate hydrate and aluminum sulfate hydrate;
[3] A method of reacting a trialkyl aluminum with water impregnated in silica gel or the like;
[4] A method of reacting a mixture of trimethyl aluminum and triisobutyl aluminum directly with water in an organic solvent such as toluene and ether;
[5] A method of reacting a mixture of trimethyl aluminum and triisobutyl aluminum with salts containing crystal water, e.g., copper sulfate hydrate and aluminum sulfate hydrate; and
[6] A method of impregnating water in silica gel or the like, and reacting it with triisobutyl aluminum, and further trimethyl aluminum.
The ionic compounds can be represented by the following formula (4).
[C+][Axe2x88x92]xe2x80x83xe2x80x83(4)
wherein [C+] represents a cation and [Axe2x88x92] represents an anion.
The cation [C+] includes those containing an active proton and not containing the proton. The cations containing the active proton can include, for example, Brxc3x8nsted acid, e.g., trimethylammonium, triethylammonium, tripropylammonium, tributylammonium, N,N-dimethylanilinium, N,N,2,4,5-pentamethylanilinium, triphenylphosphonium, tri(o-tolyl)phosphonium, tri(p-tolyl)phosphonium and tri(mesityl)phosphonium. The cations not containing it can include, for example, carbonium, oxonium and sulfonium cations.
The anions [Axe2x88x92] can include, for example, [AlR4xe2x88x92], [BR4xe2x88x92], [PR6xe2x88x92] and [ClO4xe2x88x92]. R represents a hydrocarbon group of 1-20 carbons such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, isopentyl, sec-pentyl, t-pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, benzyl and naphthyl. R may be substituted by a hydrocarbon group of 1-10 carbons or a halogen atom, examples of which can include methylphenyl, dimethylphenyl, trimethylphenyl, hexamethylphenyl, pentamethylphenyl, ethylphenyl, butylphenyl, pentylphenyl, chlorophenyl, dichlorophenyl, trichlorophenyl, hexachlorophenyl, pentachlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, hexabromophenyl, pentabromophenyl, fluorophenyl, difluorophenyl, trifluorophenyl, hexafluorophenyl and pentafluorophenyl.
An organoaluminum compound which is used together with the ionic compound as a catalyst component in the catalyst for olefin polymerization comprising the metallocene compound of the present invention can be represented by the following formula (5).
R4sAlY3xe2x88x92sxe2x80x83xe2x80x83(5)
wherein R4 represents a hydrocarbon group of 3-12 carbons, Y represents a hydrogen atom or a halogen atom and s represents an integer of 1-3.
R4 can include, for example, an alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and t-butyl, and an alkenyl group.
The halogen atom for Y can include, for example, fluorine, chlorine and bromine.
In case where the catalyst of the present invention contains the metallocene compound and aluminoxane, it is preferably used in such a range that an aluminum atom in aluminoxane is 10-100000 mols, preferably 50-50000 mols, and most preferably 100-30000 mols per mol of the transition metal atom in the metallocene compound.
The term xe2x80x9cpolymerizationxe2x80x9d as used herein means both homopolymerization and copolymerization. Accordingly, the term xe2x80x9colefin polymerxe2x80x9d includes a homopolymer of an olefin and a copolymer of two or more olefins.
The catalyst of the present invention can be used in the polymerization of olefins. The olefins which can polymerize can include straight-chain xcex1-olefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-pentene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene, and branched-chain xcex1-olefins such as 3-methyl-1-butene, 4-methyl-1-pentene and 2-methyl-1-pentene.
A mixture containing two or more olefins can be polymerized by using the catalyst of the present invention. For example, a mixture of two olefins such as ethylene/propylene and propylene/1-butene or a mixture of three olefins such as ethylene/propylene/1-butene can be polymerized to produce a random copolymer.
By employing a multi-stage polymerization process comprising plural polymerization steps and varying kinds of feed olefins in each step, for example, a block copolymer containing two or more olefin units based on the combination of olefins as mentioned above can be produced.
The catalyst of the present invention can also be used in the polymerization of the above olefin and the above mixture of two or more olefins which further contain conjugated or non-conjugated dienes such as butadiene, 1,4-hexadiene, 1,4-pentadiene, 1,7-octadiene and 1,9-decadiene, styrenes, cyclic olefins such as cyclopropene, cyclobutene, norbornene and dicyclopentadiene, and polar vinyl monomers such as acrylates and methacrylates.
The catalysts comprising the metallocene compounds of the present invention can be used in the liquid- and gas-phase polymerizations of olefins.
Solvents used in the liquid-phase polymerization can include hydrocarbon compounds capable of dissolving metallocene compounds, for example, aromatic hydrocarbons such as benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, butylbenzene, mesitylene and naphthalene. Preferably, toluene and xylene are used.
In case where solvents used in the polymerization cannot dissolve the metallocene compounds, the polymerization of olefins can be carried out in those solvents by employing the process as described in Japanese Patent Kokoku 7-96566 wherein the catalyst is preactivated by previously mixing metallocene compounds with aluminoxanes and ionic compounds or with ionic compounds and organoaluminum compounds in an aromatic hydrocarbon, followed by reacting with small amounts of xcex1-olefins. Examples of such solvents which cannot dissolve the metallocene compounds include aliphatic hydrocarbons such as butane, isobutane, pentane, hexane, heptane, octane, decane, dodecane, hexadecane and octadecane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane and cyclooctane; and petroleum fractions such as gasoline, kerosene and gas oil. In particular, aliphatic hydrocarbons are preferable. Further, olefins to be polymerized per se can be used as a solvent in the form of liquefied olefin to carry out the polymerization.
In the use of the catalyst, the present metallocene compounds previously mixed with aluminoxanes or ionic compounds or a mixture of ionic compounds and organoaluminum compounds may be supplied to a reaction system. Alternatively, the catalyst components may be supplied separately to the reaction system.
In the polymerization of olefins using the metallocene compounds of the present invention, the polymerization temperature in the reaction system is preferably from xe2x88x9250xc2x0 C. to 150xc2x0 C., most preferably from xe2x88x9210xc2x0 C. to 100xc2x0 C., but not limited thereto. The polymerization pressure is preferably in the range of from atmospheric pressure to 7 MPa, most preferably from 0.2 MPa to 5 MPa, but not limited thereto. The molecular weight of olefin polymers to be produced can be regulated by known means, for example, choice of the polymerization temperature or introduction of hydrogen.
The catalysts for olefin polymerization according to the present invention may contain two or more metallocene compounds in any proportion. Further, the catalysts of the present invention may be used in combination with other known catalysts for olefin polymerization in any proportion. The addition of the olefin polymerization catalysts of the present invention can modify olefins produced by using only known olefin polymerization catalyst. In particular, polyolefins having various physical properties can be produced by adding known metallocene compounds to the olefin polymerization catalysts of the present invention in any proportion.